1. Field of the Invention
The present invention relates to a chip type power inductor and a fabrication method thereof, and more particularly, to a small chip type power inductor in which a current limitation due to a magnetic saturation is less and a fabrication method thereof.
2. Description of the Conventional Art
Generally, a chip type inductor is divided into an inductor for a signal line and an inductor for a power line. Whereas the inductor for a signal line has a rated current corresponding to several mA˜several tens of mA, the inductor for a power line has a comparatively great rated current corresponding to several hundreds of mA˜several A.
Recently, as an electronic instrument becomes small, electronic components used therein also become small and light. However, a comparative capacity ratio of a power circuit used in the electronic instrument is increased for an entire volume of the electronic instrument. This is because each kind of LSI including a CPU used in each kind of electronic circuit becomes fast and high-integrated but magnetic components such as an inductor and a transformer which are essential circuit factors of a power circuit have a difficulty in becoming small.
When the magnetic components such as an inductor and a transformer become small and thus a capacity of a magnetic substance is decreased, a magnetic core easily becomes magnetically saturated. Accordingly, a current amount capable of being used as a power device is decreased.
As a magnetic substance used in fabricating an inductor, a Ferrite based magnetic material or a metal magnetic substance are used. The ferrite based magnetic material is mainly used in a multi-layer chip type inductor having an advantage in a mass production and a miniaturization. The ferrite has high magnetic permeability and electric resistance, but has a low saturation magnetic flux density. Therefore, if the ferrite is used as it is, an inductance is greatly lowered by a magnetic saturation and a DC bias characteristic is deteriorated. Accordingly, as the conventional power inductor, a winding type power inductor that conducting wire is wound on a metal magnetic substance having a high saturation magnetic flux density in spite of a high loss and a low electric resistance was mainly used. Also, in case of the multi-layer power inductor, a usable current range was so less.
Recently, as portable devices are rapidly increased, a demand for low consumption power components for minimizing a battery consumption is being increased. According to this, a D-class amplifier is much being used in a car-stereo, a PDA, a notebook PC, and etc. Whereas A and B class amplifiers levels amplify a signal by an amplification function (an analogue process) of a vacuum tube, a transistor, and etc. the D-class amplifier amplifies a signal by switching operation (digital processing). The D-class amplifier has a high efficiency and thus less generates heat from the inside thereof, so that large power package and heat sink can be omitted and thereby the amplifier can become small. An output of the D-class amplifier is supplied to a speaker through a low pass filter. An inductor which constitutes the low pass filter has to have low loss and high DC bias characteristics. As a power inductor for the D-class amplifier, a winding type product is mainly being used nowadays. However, as aforementioned, since the winding type product has a limitation in a small size, a small multi-layer power inductor which can be easily mounted in a portable device has been much required.